1. Field of the Invention
The present invention relates to an apparatus for cooling a fuel cell. More particularly, the present invention relates to an apparatus for cooling a fuel cell in which gases contaminated in a cooling liquid of the fuel cell is separated, and then exhausted.
2. Description of the Prior Art
In recent years, a polymer electrode fuel cell (hereinafter referred to as “PEFC”) attracted as a power source for an electric automobile can generate power even at a normal temperature, and has increasingly been put into various practical applications.
Generally, PEFC composed of a plurality of fuel cells placed, the fuel cell being formed by sectioning one side of a polymer electrolyte membrane into a cathode electrode, and sectioning another side of the polymer electrode membrane into an anode electrode. PEFC is a system which generates power through a chemical reaction between oxygen in air, which is supplied to the cathode electrode and hydrogen, which is supplied to the anode (hereinafter, this reaction is referred to as “power generation reaction”).
However, since the power generation reaction is exothermic reaction, in order to maintain stable operation with keeping the interior of the fuel cell at a constant temperature, a cooling apparatus, which removes the generated heat should be required.
Usually, a system has bee utilized in which a passage, which is completely separated from the fuel gas and oxidant gas (air) by a separator, is provided on each of the fuel cells (single cells), within the fuel cell, a cooling liquid flows between the passage and a heat exchanger, to thereby cooling the fuel cell.
However, when the fuel cell is used over a prolong period of time, a sealing member, which seals around the separator, is deteriorated, having a possibility to leak the fuel gas and the oxidant gas into the cooling liquid. The fuel gas and the like leaked into the cooling liquid would cause decreasing of cooling performance or another troubles.
Japanese Patent Laid-Open No. 2001-250570 suggests a technique wherein in a heat-exchanging system, which supplies a heat-exchanging medium to the fuel cell, means for detecting the fuel gas is provided on at least one portion of the heat exchanging means and the interior of the heat-exchanging medium passage, for example, on a radiator cap residing on the top portion of a radiator (heat exchanger) or a portion at which the gases separated from the cooling liquid are collected, the gases separated from the cooling liquid are detected by the means for detecting the fuel gas to warn when the leakage of the gas such as the fuel gas into the cooling liquid is detected.
If the fuel gas or such is leaked into the cooling medium, the conventional technique can detect the leakage before the concentration of the fuel gas or such reaches a prescribed amount to warn, and if the concentration is increased thereafter, procedures such as stopping the operation of the fuel cell can be made. However, in the conventional technique, in this case, personal maintenance such as removal of the collected gas from the cooling liquid within the heat exchanger or circulation passage should be made, which reduces easy-to-use the fuel cell. Furthermore, once the concentration of the fuel gas in the cooling liquid becomes high, the cooling liquid must be exhaust as its concentration of the fuel cell is high.
In light of such situations, the present invention has been made. An object of the present invention is to provide an apparatus for cooling a fuel cell, which can dilute the fuel cell introduced into the cooling liquid to a lower concentration, making it possible to exhaust the cooling liquid with a low concentration of the fuel gas, and to enhance the operability of the power generation system through the fuel cell, by exhausting the gas, which has hitherto been left collected within the heat-exchanger and the circulation passage of cooling liquid, at any time without requiring personal maintenance whereby the concentration of the fuel gas in the cooling liquid can be maintained at a low level and the cooling performance of the apparatus for cooling the fuel cell can be prevented.